Inducible nitric oxide synthase and cytokine pattern in lesions of patients with American cutaneous leishmaniasis

Abstract

American tegumentary leishmaniasis has three forms: localized (LCL), found in resistant individuals; diffuse (DCL), found in susceptible individuals; and intermediate cutaneous leishmaniasis (ICL), found in individuals with exacerbated immunity. We evaluated cytokines and inducible nitric oxide synthase (iNOS) in lesions of LCL, ICL and DCL using immunohistochemistry. LCL granulomas showed a preponderance of interferon (IFN)-c and interleukin (IL)-12 expression, whereas ICL granulomas had more IL-4-, IL-10- and mainly transforming growth factor (TGF)-b1-expressing cells. Higher densities of iNOS+ cells were observed in ICL and LCL than in DCL. iNOS was also expressed in keratinocytes of LCL and ICL lesions, and in epidermal dendritic cells of ICL lesions. In LCL and ICL, most keratinocytes expressed IL-12 and a portion expressed IFN-c. IL-12+ and IFN-c+ dendritic cells were absent or sparse in LCL and ICL epidermis. Our results show the importance of iNOS, IL-12 and INF-c in LCL and ICL lesions, emphasizing the existence of a mixed cytokine pattern in ICL different from the Th1 and Th2 responses established in LCL and DCL lesions.